Adjustable-lens systems may be useful in a variety of devices, including eyeglasses, cameras, and virtual or augmented reality (“VR/AR”) systems, such as to adjust the focus of a display element (e.g., screen) or of a real-world image viewed by a user. The actuation of liquid lenses and other deformable optical lens assemblies generally involves generating forces in the range of about 1N-10N by an electromechanical actuator, depending on the amount of optical power shift desired and the size and construction of the optical lens assembly. Deformable portions of the optical lens assemblies may react to such forces with displacement distances in, for example, the hundreds of microns to millimeter range.
Electromechanical actuators for optical lens assemblies are conventionally designed to be small and lightweight to be considered viable as a consumer-wearable product for a head-mounted display (“HMD”), such as VR/AR glasses or headsets. In addition, the displacement capacity of some small actuators, such as piezoelectric devices, is often dependent on a reaction force of the load, which generally increases over the actuation stroke in the case of deforming portions of optical lens assemblies. Accordingly, the design of actuation mechanisms for HMDs may involve balancing several factors, such as stroke distance capabilities, force capabilities, size, and weight.